Producing metallic layers on printing sheets using a foil transfer method is known. For example, a printing material and a printing device that uses this material is described in EP 0 569 520 B1. In that reference, a sheet processing machine is disclosed that includes a sheet feeder and a sheet delivery unit. Printing units and a coating module are located between the sheet feeder and delivery units. In at least one of the printing units, an adhesive pattern is applied using a flat printing process. This adhesive pattern is applied using a cold printing process and has a particular image-forming design. A foil guide is located in the coating module following the printing unit which includes an impression cylinder and press cylinder. The foil guide is designed such that a foil strip or transfer foil is moved from a foil supply roll through a transfer gap in the coating module between the impression cylinder and the press cylinder. The foil strip is rewound on the outlet or delivery side after leaving the coating module. The transfer foil includes a carrier layer on which image-forming layers, such as metallic (e.g., aluminum) layers, can be applied. A separating layer is arranged between the metallic layer and the carrier foil to ensure that the metallic layer can be removed from the carrier layer.
When printing sheets are transported through the printing unit, each printing sheet is provided with an adhesive pattern. The printing sheet is then guided through the coating module, wherein the printing sheet resting upon the impression cylinder is brought into contact with the foil material via the press cylinder. In this case, the metallic layer that is positioned on the bottom makes a tight bond with the areas of the printing sheet provided with the adhesive. As the printing sheet continues to move forward, the metallic layer adheres only in the area of the adhesive pattern. As a result, the metallic layer is removed from the carrier foil in the area of the adhesive pattern. The consumed transfer foil is then rewound. The printing sheet is delivered in the coated state.
It is known to use of coating modules of this type in printing units of printing machines. However, a disadvantage of these modules is that they cannot be employed in a flexible manner. Moreover, such modules consume a considerable amount of transfer foil.